Electric machines, e.g., multi-phase electric motor/generators have stator windings that are energized by alternating current from inverter modules that electrically connect to high-voltage DC electrical power buses. During specific operating conditions, including high-speed, low or no load conditions, an electric machine, e.g., a permanent magnet (PM) motor may operate in an uncontrolled generator (UCG) mode, wherein motor back-emf increases, resulting in a motor output voltage that is greater than voltage on the high-voltage bus. This excess output voltage may result in a charging current flow through one or more of the diodes arranged in parallel to the switches of the inverter to the high-voltage battery. The charging current flow occurring in the UCG mode may result in excess current through components of the inverter or overcharging of the high-voltage battery that can negatively affect service life of the inverter or the high-voltage battery. Designers may select electrical component design factors and derating schemes that comprehend occurrence of excess charging in UCG modes.